The present invention relates in general to a laser transmitter, and, more particularly, to a system and method for aligning a laser transmitter so that a laser beam projected by the laser transmitter defines a plane having desired slopes in a desired direction.
Laser light systems have been employed in numerous surveying and construction applications. In one type of system, a laser light transmitting device provides a rotating laser beam which establishes a reference plane. Typically, the rotating laser beam is used to provide a continuous plane of light that creates either a constant horizontal bench mark of elevation or a selected plane over an entire work area. The laser light is either detected by the naked eye or by one or more laser beam detectors, placed at considerable distances from the transmitting device. Various construction tasks may be performed based on the visual perception of the laser light. Alternatively, detectors may be used to intercept the rotating laser beam and determine a proper elevation and grade at selected points throughout the work area.
In one type of laser light transmitting device, the plane of light is produced by projecting the beam generally upward and then deflecting the beam ninety degrees with a pentaprism or penta-mirror assembly. The pentaprism assembly is rotated about a vertical axis, thus rotating the beam and defining the reference plane. The plane of light may be tilted to a desired slope along with one or more axes by offsetting the laser light transmitting device with respect to a generally horizontal plane. The laser light transmitting device must be properly aligned about one of the axes so that the laser light accurately defines the reference plane with the desired slope.
Typically, the laser transmitting device is aligned by positioning the device so that alignment grooves located on the top of the device point in the desired direction of the slope. Alternatively, a telescope mounted on the top of the device may be used in place of the grooves to provide another visual means for aligning the transmitting device in the desired direction of the slope. Both mechanisms for aligning the transmitting device require a number of field iterations to properly align the transmitting device. Further, both mechanisms for aligning the transmitting device are inaccurate considering that an offset of a couple of degrees results in relatively large error over the entire work site.
Accordingly, there is a need for a system for aligning a laser transmitter so that a laser beam projected from the laser transmitter accurately defines a plane with a desired slope. Preferably, such a system would be automatic, easy to operate and relatively inexpensive.